Lifetime extension in green thermally activated delayed fluorescent organic light-emitting diodes by increasing excited state bond dissociation energy

Ho Jung Lee; Si Hyun Han; Wan Pyo Hong; Ok-Keun Song; Jun Yeob Lee

Journal of Industrial and Engineering Chemistry, Vol.69, 364-369, January, 2019

DOI10.1016/j.jiec.2018.09.040 Export Citation

Lifetime extension in green thermally activated delayed fluorescent organic light-emitting diodes by increasing excited state bond dissociation energy

Ho Jung Lee, Si Hyun Han, Wan Pyo Hong¹, Ok-Keun Song¹, and Jun Yeob Lee^†

School of Chemical Engineering, Sungkyunkwan University, 2066, Seobu-ro, Jangan-gu, Suwon-si, Gyeonggi-do, 16419, Republic of Korea
¹LG Science Park, LG Chem, Ltd., 30, Magokjungang 10-ro, Gangseo-gu, Seoul, 07796, Republic of Korea

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A lifetime extending molecular design approach by increasing the bond dissociation energy of the thermally activated delayed fluorescent (TADF) emitters was investigated. A TADF emitter with a molecular design having the donors in a planar manner, 4-(9H-carbazol-9-yl)-6-(9,9"-diphenyl- 9H,9'H,9"H-[3,3':6',3"-tercarbazol]-9'-yl)isophthalonitrile (TCzIPN), was compared with state of the art green TADF emitter. The two emitters were green TADF emitters with similar peak wavelengths, but the TCzIPN exhibited three times longer lifetime than the current TADF emitter. Analysis of bond dissociation energy of the TADF emitters revealed that the weak C-N bond of the TCzIPN was stabilized by small dihedral angle between donor and an aromatic linker. This was confirmed by exciton stability test of the emitters, and the C-N bond stabilization effect in triplet excited state was well correlated with the lifetime improvement of the TCzIPN devices.

Keywords:Lifetime;Bond dissociation energy;Organic light-emitting diodes;Thermally activated delayed;fluorescence;Geometry

[References]

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Lee SY, Yasuda Y, Nomura H, Adachi C, Appl. Phys. Lett., 101, 093306 (2012)
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Li B, Nomura H, Miyazaki H, Zhang QS, Yoshida K, Suzuma Y, Orita A, Otera J, Adachi C, Chem. Lett., 43(3), 319 (2014)
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Cho YJ, Yook KS, Lee JY, Sci. Rep., 5, 7859 (2015)
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[1] Uoyama H, Goushi K, Shizu K, Nomura H, Adachi C, Nature, 13, 234 (2012)

[2] Lee SY, Yasuda Y, Nomura H, Adachi C, Appl. Phys. Lett., 101, 093306 (2012)

[3] Im Y, Lee JY, J. Inf. Disp., 18, 101 (2017)

[4] Tao Y, Yuan K, Chen T, Xu P, Li HH, Chen RF, Zheng C, Zhang L, Huang W, Adv. Mater., 26(47), 7931 (2014)

[5] Lee DR, Kim BS, Lee CW, Im Y, Yook KS, Hwang SH, Lee JY, ACS Appl Mater. Interfaces, 7, 9625 (2015)

[6] Zhang DD, Cai MH, Zhang YG, Zhang DQ, Duan L, Mater. Horiz., 3, 145 (2016)

[7] Shizu K, Noda H, Tanaka H, Taneda M, Uejima M, Sato T, Tanaka K, Kaji H, Adachi C, J. Phys. Chem. C, 119, 26283 (2015)

[8] Zhang QS, Li B, Huang SP, Nomura H, Tanaka H, Adachi C, Nat. Photonics, 8, 326 (2014)

[9] Nakanotani H, Masui K, Nishide J, Shibata T, Adachi C, Sci. Rep., 3, 2127 (2013)

[10] Cho YJ, Jeon SK, Lee JY, Adv. Opt. Mater., 4, 688 (2016)

[11] Kim M, Jeon SK, Hwang SH, Lee JY, Adv. Mater., 27(15), 2515 (2015)

[12] Li B, Nomura H, Miyazaki H, Zhang QS, Yoshida K, Suzuma Y, Orita A, Otera J, Adachi C, Chem. Lett., 43(3), 319 (2014)

[13] Park WJ, Lee Y, Kim JY, Yoon DW, Kim J, Chae SH, Kim H, Lee G, Shim S, Yang JH, Lee SJ, Synth. Met., 209, 99 (2015)

[14] Oh CS, Choi JM, Lee JY, Adv. Opt. Mater., 4, 1281 (2016)

[15] Hirata S, Sakai Y, Masui K, Tanaka H, Lee SY, Nomura H, Nakamura N, Yasumatsu M, Nakanotani H, Zhang QS, Shizu K, Miyazaki H, Adachi C, Nat. Mater., 14(3), 330 (2015)

[16] Kaji H, Suzuki H, Fukushima T, Shizu K, Suzuki K, Kubo S, Komino T, Oiwa H, Suzuki F, Wakamiya A, Murata Y, Adachi C, Nat. Commun., 6, 8476 (2015)

[17] Kim M, Jeon SK, Hwang SH, Lee SS, Yun E, Lee JY, J. Phys. Chem. C., 120, 2485 (2016)

[18] Cho YJ, Yook KS, Lee JY, Sci. Rep., 5, 7859 (2015)

[19] Kim M, Jeon SK, Hwang SH, Lee SS, Yu E, Lee JY, Chem. Commun., 52, 339 (2016)

[20] Im Y, Kim M, Cho YJ, Seo JA, Yook KS, Lee JY, Chem. Mater., 29, 1946 (2017)

[21] Song W, Lee JY, Adv. Opt. Mater., 5, 160090 (2017)